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Kamkin, A. N.; Zhou, Guanyu; Давыдов, А. Д.

doi:10.1023/a:1004845920425

Cited by 8 publications

(5 citation statements)

References 13 publications

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“…19 By averaging the V * values for different wavelengths, a V FB Х −0.55 ± 0.05 V͑SCE͒ has been assumed for the anodic oxide on the Al-53 atom % Ti alloys. V FB estimated for the anodic film on Al-53 atom % Ti alloy is more cathodic than that reported for thin anodic films on a Al-50 atom % Ti alloy, 32 obtained by fitting the photocharacteristics in a rather limited region of electrode potentials with n = 2. Such a value of n, usually predicted for crystalline semi-conductors, occurs with amorphous semiconductors with appropriate distributions of states within the gap and collection lengths.…”

Section: Resultsmentioning

confidence: 92%

Effect of Composition on the Photoelectrochemical Behavior of Anodic Oxides on Binary Aluminum Alloys

Santamaria

Quarto

Skeldon

et al. 2006

J. Electrochem. Soc.

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The photoelectrochemical behavior of anodic films on Al alloys, containing titanium, tantalum, and tungsten ͑valve metals͒, has been studied as a function of alloy composition and anodizing conditions. Photocurrent spectroscopy has been used to get information on bandgap and the flatband potential values of different mixed oxides. Both insulator-like and semiconducting behavior has been observed for anodic oxides grown on Al-W and Al-Ti alloys dependent on alloy initial composition. Anodic films on valve metals alloys are of interest for investigating mechanisms of oxide growth; different works 1-6 have mainly focused their attention toward their morphology, structure, and composition to get insights on mechanism of anodic oxidation and ionic transport in "mixed oxides." Because these films are also of interest for possible application in electronics, for instance in metal-oxide semiconductor junctions [7][8][9][10][11][12] or in dye-sensitized photoelectrochemical and solid-state solar cells, 13,14 the possibility of controlled modification of the solid-state properties, such as bandgap, flatband potential, and dielectric constant, by use of "mixed oxides," is appealing from practical and theoretical viewpoints. This aspect becomes more important if we consider the prominent role of the solid-state properties of passive layers in controlling also the pitting behavior of metals and alloys. [15][16][17] Notably, it has been proposed that the bandgaps of crystalline binary oxides correlate with the electronegativities of their constituents, thus suggesting the possibility to predict the bandgaps of ternary oxides, 18-20 using an average electronegativity parameter for the cationic group and hence, tailoring of oxide properties. The correlation can apply also to amorphous oxides if account is taken of the influence of disorder on the optical bandgap value. 20,21 In the present work, a study of the solid-state properties of anodic films on several Al alloys was carried out by using photocurrent spectroscopy ͑PCS͒ to measure their bandgap and flatband potential. The validity of the above mentioned correlation was tested to get information about its applicability and limits. ExperimentalAl-23 atom % Ti, Al-53 atom % Ti, and Al-34 atom % Ta alloys, prepared by physical vapor deposition, and Al-W alloys, containing 15, 23, and 77 atom % W, prepared by dc magnetron sputtering, were anodized either potentiodynamically, at 100 mV s −1 , or galvanostatically, at 5 mA cm −2 in either 0.1/0.01 M ammonium pentaborate electrolyte ͑ABE͒, of pH 8.5, or 0.01 N H 2 SO 4 solution at room temperature. A three-electrode cell, with a saturated calomel electrode ͑SCE͒, and a two-electrode cell with a platinum cathode, were used in potentiodynamic and galvanostatic experiments, respectively.The composition of Al-W alloys and anodic oxides grown on them were analyzed by Rutherford backscattering spectroscopy ͑RBS͒, using 1.83 MeV He + ions supplied by the Van de Graaff accelerator of the University of Paris. The scattered ions were detect...

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Section: Resultsmentioning

confidence: 92%

Effect of Composition on the Photoelectrochemical Behavior of Anodic Oxides on Binary Aluminum Alloys

Santamaria

Quarto

Skeldon

et al. 2006

J. Electrochem. Soc.

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“…34 We think the Fenton-like reaction occurs more readily under irradiation since the semi-conducting oxide nanoparticles become conducting due to photons with a wide range of energy. The band gap of CoO/Co 3 O 4 has been reported to be in a range of 1.4-2.1 eV 35 and electrocatalytic properties of cobalt oxides 36,37 have been reported in the literature.…”

Section: Effects Of Ph and Dissolved Oxygenmentioning

confidence: 99%

Gamma-radiolysis-assisted cobalt oxide nanoparticle formation

Alrehaily

Joseph

Biesinger

et al. 2013

Phys. Chem. Chem. Phys.

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The formation of Co(3)O(4) nano-scale colloid particles by gamma irradiation of CoSO(4) solutions was investigated. Solutions of 0.2-0.3 mM CoSO(4) at pH 6.0 and 10.6 (air-saturated and Ar-purged) were irradiated at an absorbed dose rate of 5.5 kGy h(-1). The resulting concentrations of H(2), H(2)O(2), Co(II) and Co(III) species in solution and the chemical composition and sizes of particles that were formed were measured as a function of irradiation time. Particle formation was observed only for initially air-saturated CoSO(4) solutions at pH 10.6. Analysis of the particle formation as a function of irradiation time shows that the particles evolve from Co(OH)(2) to CoOOH and then to Co(3)O(4). The radiolytic oxidation of Co(II) to Co(III) was completed in 100 min and the chemical composition of the final particles was identified as Co(3)O(4) by XPS, Raman and UV-Vis spectroscopy. Transmission electron microscopy (TEM) images show the final particles are approximately uniform in size, ranging from 8 to 20 nm. A mechanism is proposed to explain the particle formation. A key factor is the low solubility of Co(OH)(2) in air-saturated solutions at high pH. This mechanism for particle formation is compared with the mechanism previously reported for the radiolytic formation of γ-FeOOH nanoparticles.

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“…Two pair of peaks A1/C1 and A2/C2 appearing in the repetitive cycling can be ascribed to the following electrode reactions [14][15][16]:…”

Section: Abrasive Stripping Voltammetry Studiesmentioning

confidence: 99%